Short-term variation of cosmic ray diurnal anisotropy and solar activity

A correlative analysis has been made between cosmic ray intensity and solar activity (sunspot numbers) during high amplitude days for the period 1991–1995. The high amplitude days with the time of maximum in the corotational/azimuthal direction do not indicate any significant correlation with solar activity. The diurnal amplitude significantly remains constant and high (0.5%) during the entire period. Our observations suggest that the direction of the anisotropy of high amplitude anisotropic wave train events contribute significantly to the short-term behavior of the cosmic ray diurnal anisotropy. The correlation coefficient is found to remain positive during solar activity maximum for all the high amplitude anisotropic wave train events.     

Optimum conditions of observation of tubular-loop structures of the interplanetary magnetic field and estimation of their lifetime

Basic conditions of observation of IMF tubular-loop structures are considered on the basis of experimental data of studying the fluxes of solar cosmic ray protons in the interplanetary medium. Lifetime of these structures, when their sources disappear on the Sun, is estimated.     

The reflection model for propagation of solar cosmic rays

The principles of constructing the model are considered in this paper, together with the issues of its components and physical algorithm. The main emphasis is placed on the cause-and-effect relationships between the structure and dynamics of the solar and interplanetary media and the motion of solar cosmic ray particles. The specific features of the initial phase of motion of the particles after their acceleration in a solar flare are considered, as well as the subsequent phase of further particle propagation in the solar corona, and the phase of motion in the heliosphere. The processes of transport of charged particles in flare plasma ejections are considered in detail.     

滚动姿态对阳光与卫星向阳面夹角的影响分析

采用理论分析方法分析了卫星绕滚动轴滚动后,卫星向阳面与阳光的夹角的变化情况,用热分析工程软件NEVADA的数值计算反推结果,对理论分析结果进行了验证。分析结果表明：卫星姿态绕滚动轴滚动后,阳光与卫星向阳面的夹角相对于β角在不同纬度的变化趋势将不同,但在轨道周期内将发生周期性变化;随着滚动角的增大,该夹角的变化幅度也将增大。研究成果对卫星外热流分析具有参考意义。     

Cosmic ray impact on extrasolar earth-like planets in close-in habitable zones

Because of their different origins, cosmic rays can be subdivided into galactic cosmic rays and solar/stellar cosmic rays. The flux of cosmic rays to planetary surfaces is mainly determined by two planetary parameters: the atmospheric density and the strength of the internal magnetic moment. If a planet exhibits an extended magnetosphere, its surface will be protected from high-energy cosmic ray particles. We show that close-in extrasolar planets in the habitable zone of M stars are synchronously rotating with their host star because of the tidal interaction. For gravitationally locked planets the rotation period is equal to the orbital period, which is much longer than the rotation period expected for planets not subject to tidal locking. This results in a relatively small magnetic moment. We found that an Earth-like extrasolar planet, tidally locked in an orbit of 0.2 AU around an M star of 0.5 solar masses, has a rotation rate of 2% of that of the Earth. This results in a magnetic moment of less than 15% of the Earth's current magnetic moment. Therefore, close-in extrasolar planets seem not to be protected by extended Earth-like magnetospheres, and cosmic rays can reach almost the whole surface area of the upper atmosphere. Primary cosmic ray particles that interact with the atmosphere generate secondary energetic particles, a so-called cosmic ray shower. Some of the secondary particles can reach the surface of terrestrial planets when the surface pressure of the atmosphere is on the order of 1 bar or less. We propose that, depending on atmospheric pressure, biological systems on the surface of Earth-like extrasolar planets at close-in orbital distances can be strongly influenced by secondary cosmic rays.     

Cosmic-ray propagation through the disturbed heliosphere

The stationary, source-free, one-dimensional solution to the cosmic-ray heliospheric transport equation was solved using Runge–Kutta methods. These calculations have been applied to the treatment of Forbush decreases and the evolution of the solar cycle through the heliosphere. Forbush decreases calculated by this method produce spectra that are in good agreement with both the theoretical heliocentric potential and the potential as determined from neutron monitor data. During solar modulation, the effect of the travelling disturbance is to flatten the gradient of the cosmic ray flux in the inner heliosphere at solar minimum and steepen the gradient at solar maximum, as the incoming cosmic rays see solar activity up to a year earlier. The resulting spectra at the earth's orbit are in good agreement with the heliocentric approximation. The heliocentric approximation is an accurate and convenient method of accounting for solar modulation.     

Spectral analysis of ionospheric disturbances in the phase delay and radio signal amplitude at limb paths according to the <Emphasis Type="Italic">COSMIC</Emphasis> data in periods of solar activity

Based on more than 4500 sessions of radio transillumination of Earth’s atmosphere along the satellite–atmosphere–satellite path obtained in the COSMIC experiment, the distribution along latitude and over local time of the spatial spectra of variations in the ionospheric phase delay and signal amplitude has been analyzed. The spatial spectra have been calculated for two height ranges, i.e., 60–80 and 80–100 km. In the phase signal spectrum within the height range 80–100 km, the second maximum in the vicinity of a frequency of 7–8 rad/km is clearly seen. Its diurnal and latitudinal behavior and its decrease towards high latitudes in both hemispheres can also be seen. In the height range of 60–80 km, this maximum is hardly observed. Although solar flares can lead to substantial local changes in the electron concentration, no substantial difference in the behavior of the spectral densities of the amplitude and phase delay at long limb paths was observed within these two height ranges on days of active and quiet sun. The latter fact makes it possible to develop a united algorithm of optimal ionospheric correction of the radio occultation data independent of solar activity.     

Specific features of solar cosmic ray fluxes and geomagnetic conditions on December 5–18, 2006

Results of the analysis of specific features of solar activity, dynamics of solar cosmic ray fluxes, and state of the interplanetary medium are presented for the period December 5–18, 2006. The data analysis is based on new model concepts on coronal and interplanetary propagation of solar cosmic rays: partial capture into the magnetic field traps and oscillations at reflections from magnetic mirrors. Some new hypotheses about possible relations of the features of the interplanetary medium with processes in the Earth’s magnetosphere are put forward: the influence of the discrete interplanetary medium on processes in the Earth’s magnetosphere does exist always and, in this sense, it is a fundamental phenomenon; the discreteness of the inter-planetary medium can be one of the causes of geomagnetic substorms.     

Variations in rigidity spectrum and anisotropy of cosmic rays during sporadic phenomena in the heliosphere in October–November 2003

The variations in the cosmic ray (CR) anisotropy have been studied by the method of spectrographic global survey in the period from October 1 to November 30, 2003. The data of ground-based observations of CR intensity measured by the world network of stations were used. It is shown that at some instants of the period under investigation a bidirectional anisotropy of large amplitude (tens of percent) is observed in the angular distribution of particles. This indicates, first, a carryover of looplike structures of the interplanetary magnetic field (IMF) by coronal mass ejections and, second, a high degree of regularity of the IMF in these structures. The maximum amplitude of the bidirectional anisotropy (for particles with a rigidity of 4 GV) was observed on October 29 and 31 (50% and 30%, respectively) and on November 21–24 (15%). Using the data of ground-based and satellite measurements of the CR intensity in the period under study, we have investigated variations of the rigidity spectrum of protons in the energy range from 15 MeV to tens of GeV. The analysis was carried out in the context of the model of CR modulation by regular electromagnetic fields of the heliosphere. Parameters of the model rigidity spectrum of CRs are determined for every hour of observation. Using their values we have estimated the characteristics of electromagnetic fields of the solar corona and heliosphere that were responsible for powerful sporadic phenomena from the end of October to the beginning of November and after November 20, 2003.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 645–652.Original Russian Text Copyright © 2004 by Dvornikov, Sdobnov, Yudina.     

Motion and transport of solar cosmic rays in heliospheric traps: The event on January 28–31, 2001

The results of studying the enhancement of solar cosmic ray fluxes on January 28?C31, 2001 in a wide energy range are presented using the ACE spacecraft data. A comparative analysis of temporal variations of the fluxes of charged particles and of the interplanetary medium parameters (interplanetary magnetic field and solar wind) has been performed on the basis of the ??reflection?? model of motion, accumulation, and modulation of cosmic rays. It is shown that a magnetic trap for solar cosmic rays was created by a plasma stream and flare ejection from an active region in the western part of the solar disk. Particles of low energies (<10 MeV) were captured inside the trap; the dispersion of distribution of particles with different energies inside the trap being determined by its complicated magnetic structure. The power-low dependence of the time of maximum for the flux of particles on their energy is found, and softer energy spectrum inside the trap is explained.     

中国上空过渡流区大气月平均状态的模拟结果

利用美国海军研究实验室在MSIS系列模型基础上发展的大气模型NRLMSISE-00, 模拟研究了2001年—2013年中国上空过渡流区80～140 km高度的大气状态。对于中国东部和中部过渡流区, 基于模拟数据得到的月平均结果显示大气密度和温度呈现一致的变化趋势, 还表现出与太阳活动的显著关联。谱分析的结果显示, 在90 km高度以上大气密度呈现半年周期变化, 在90～110 km高度范围这种半年变化的幅度随纬度增大。在100 km高度, 上半年出现的半年周期过程中密度的最大、最小值分别出现在3月和6月, 明显超前中、高热层的半年周期过程。     

Sporadic structures and small-scale irregularity in the nighttime polar ionosphere in the period of high solar activity according to the data of radio occultation measurements on satellite-to-satellite paths

Results of the analysis of 327 sessions of radio occultation on satellite-to-satellite paths are presented. The data are taken in the nighttime polar ionosphere in the regions with latitudes of 67°–88°, and in the period of high solar activity from October 26, 2003 to November 9, 2003. Typical ionospheric changes in the amplitude and phase of decimeter radio waves on paths GPS satellites-CHAMP satellite are presented. It is demonstrated that these data make it possible to determine characteristics of the sporadic E _s structures in the lower ionosphere at heights of 75–120 km. Histograms of distribution of the lower and upper boundaries, thickness, and intensity of the E _s structures are presented. Dispersion and spectra of amplitude fluctuations of decimeter radio waves caused by small-scale irregularity of the ionospheric plasma are analyzed. The relation of the polar E _s structures and intensity of small-scale plasma irregularity to various manifestations of solar activity is discussed. The efficiency of monitoring the ionospheric disturbances caused by shock waves of the solar wind by the radio occultation method on satellite-to-satellite paths is demonstrated.     

影响GEO卫星长寿命高可靠的空间环境因素及其评估、验证和保障技术研究

文章叙述了空间环境与卫星长寿命高可靠的关系,着重分析了影响GEO卫星长寿命高可靠的各种空间环境效应,如:地磁亚暴电子造成的卫星表面带电及诱导的二次放电、辐射带高能电子引起卫星内带电、太阳耀斑质子和银河宇宙射线造成的单粒子效应、空间带电粒子和太阳电磁辐照造成的辐照总剂量效应以及空间环境下敏感表面的污染效应等.文章最后给出GEO卫星空间环境效应的评估、验证和保障技术研究的必要性及其主要研究方向.     

地球边缘大气密度时空特性分析

分析了地球边缘大气密度的时变特性及空间分布特性。从物理原因出发并基于NRLMSISE-00和MET-99大气模型计算随不同时空变量变化的相对大气密度,以说明各时空因素对地球边缘大气密度的影响程度。分析结果表明地球边缘大气密度具有较强的时变特性,昼夜和季节均对大气密度产生一定影响。空间特性表现为纬度对大气密度的影响明显,而经度影响微弱。季节不同导致纬度的影响程度不同,纬度因素在夏季和冬季的影响强于春秋。随着纬度的增加,季节对地球边缘大气密度的影响逐渐增强,而当地时间的影响呈减弱趋势。相比较而言,低纬区的昼夜波动强于季节波动,高纬区的季节波动强于昼夜波动。     

Changes in the Earth’s ozonosphere due to ionization of high-latitude atmosphere by solar protons in October, 2003

Using the data of the Russian KORONAS-F satellite and American GOES spacecraft on solar cosmic ray fluxes associated with powerful events which occurred on the Sun at the end of October - the beginning of November, 2003, calculations of ionization of high-latitude (70° N) atmosphere were carried out. The calculations have shown that the maximum values of ionization for the chosen latitude lie in the range of 50–70 km. The largest ionization was caused by the flare on November 28, 2003. Based on a numerical photochemical simulation it is shown that, as a result of intensification of catalytic cycles with participation of ozone-destroying NO and OH, the concentration of ozone decreased by 30% at ionization maximum altitudes.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 653–662.Original Russian Text Copyright © 2004 by Krivolutsky, Kuminov, Vyushkova, Kuznetsov, Myagkova.     

Dynamics of Quasi-Biennal Variations of Cosmic Rays and Solar Activity

The quasi-biennial variations in the flux of galactic cosmic rays (GCRs) have been studied based on the data of stratospheric sensing and measurements by neutron monitors, as well as in various manifestations of solar activity and interplanetary medium parameters. It has been shown that quasi-biennial GCR variations are caused by variations with the same period in the mean magnetic field of the Sun that coincide with them over time and have been identified in the anti-phase, which respond to the sign of this field. The variations in the quasi-biennial cosmic ray are caused by quasi-biennial variations in the mean magnetic field of the Sun via the quasi-biennial variations in the interplanetary magnetic field.     

A Series of Proton Flares in July 1985 from Observations by the Prognoz-10 Satellite and Vega-1, 2 Spacecraft

The enhancements of solar protons with an energy of more than 30 MeV, originating from flares in one active region and observed simultaneously aboard three spacecraft Vega-1, 2 and Prognoz-10 in July 1985, are analyzed and approximated in this work by using the reflection model [2]. The numerical values of several physical parameters (the parameters of distribution of solar cosmic ray (SCR) particles inside heliosphere traps, the coefficients of trap transparency) that are not observed by direct measurements are estimated.     

To the problem of spectrum investigation with an on-board analyser VAR

The spectrum analysis of low frequency processes on board the satellite becomes inevitable in connection with the investigation of the thin structure of specific areas in magnetosphere, main shock wave and solar wind. The necessity to perform the analysis in a rather short period of time is a peculiarity of the thin structure investigation procedure. The evaluation of drawbacks and advantages of various spectral analysis techniques shows that the discrete Fourier transform (DFT) method is most efficient for the case. It enables us to perform a parallel analysis of several processes in different frequency subranges. The amplitudes and frequencies of polyharmonic processes and spectral power of low frequency random processes are determined. The technique described in this paper has been developed at the Institute for Physics and Mechanics of the Ukr. S.S.R. Academy of Sciences to determine the amplitudes and frequencies of the polyharmonic processes components. The analyser VAR designed at the Institute is supposed to be utilized in international cosmic tests.     

Galactic cosmic rays and parameters of the interplanetary medium near solar activity minima

The time behavior of intensity of cosmic rays with relatively low (~1–6 GeV) and high (>10 GeV) energies are considered together with characteristics influencing the modulation of cosmic rays in the heliosphere. The periods under study are close to solar activity minima in cycles 21/22, 22/23, and 23/24. Diffusion and convection in small-scale magnetic fields of the heliosphere are demonstrated to play some role only at sufficiently weak disturbances of the field (B/δB > 1.3). In this case, a negative correlation is observed between B/δB and a tilt of the surface of the heliospheric current sheet. The analysis of characteristics of the interplanetary medium in periods of solar activity minima shows that the energy anomaly of cosmic rays in the minimum of cycles 23/24 is caused by deficit of high energy particles rather than by an excess of particles of relatively small energies.     

On the relationship between quasi-biennial variations of solar activity,the heliospheric magnetic field and cosmic rays

Quasi-biennial oscillations (QBO) of solar activity (T ≈ 1–4 years) are considered to be a variation of basic solar activity, associated with the solar dynamo process. They are transferred into interplanetary space by the open magnetic flux of the Sun, generating QBO in the intensity of cosmic rays (CR). This paper discusses the observational characteristics of QBO in CR and their relationship with QBO on the Sun and in the interplanetary medium. The delay time of QBO in CR relative to the solar and heliospheric magnetic field suggests that the formation of QBO in the open magnetic flux of the Sun occurs within 3–5 months. The paper considers the question of the prominent periodicity of CR (T = 1.6 years) that has prevailed in CR and in the heliospheric magnetic field for more than 10 years but was not stable over 60 years of observations. Distinctions in the characteristics of QBO and long-term variations of CR suggest features of the mechanism of their formation.